Polysiloxanes, especially silicone rubber, find use in the most widely differing fields of technology and medicine. Silicone rubber has a high oxygen permeability, for which reason this material would also be expected to be suitable for the manufacture of contact lenses. However, silicone rubber is a hydrophobic material and has therefore not been able to gain acceptance as a contact lens material, for which hydrophobicity causes problems. Various processes are known for hydrophilizing this material (European Patent 0,033,754, German Offenlegungsschrift 3,004,685, U.S. Pat. Nos. 4,143,949 and 3,925,178, French Patent 2,407,232, German Auslegeschrift 2,353,495 and German Auslegeschrift 2,164,805).
From the U.S. Pat. No. 4,332,922, a process is already known for hydrophilizing contact lenses of silicone rubber by providing the surface of the silicone rubber with a hydrophilic layer. This process comprises two steps. In a first step of the process, the silicone rubber is reacted with an oligomeric, SiH-group-containing siloxane in the presence of a catalyst (equilibration reaction) and, in a second step of the process, the equilibrated silicone rubber is subjected either to a reaction with an aqueous base or to a silane addition reaction with compounds containing C.dbd.C double bonds. By these means, a silicone rubber with good oxygen permeability is obtained, the surface of which has been made hydrophilic but does not exhibit any increased tendency to form deposits in spite of the high hydrophilicity.
It is an object to the present invention to provide a molded silicone article by means of a process which is an improvement over these known hydrophilizing processes in that only one process step namely only the equilibration reaction, need be carried out in order to make the surface of the molded silicone rubber article hydrophilic.